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NW Fishletter #335 July 24, 2014
 Aussies Say El Niño's On Hold For Now
The latest El Niño/Southern Oscillation update from Australia's Bureau of Meteorology says most climate models still point to an El Niño event next fall, but "it is increasingly unlikely to be a strong event." The July 15 report said some cooling has occurred in the tropical Pacific because of a general lack of atmospheric response.
Sea surface temperatures remain above normal in the western and eastern tropical Pacific, but the central Pacific has cooled to near-average temperatures. "More broadly," the report noted, "positive anomalies also remain in areas of the Indian Ocean and in large areas of the northern Pacific Basin, in both the East China Sea and along the North American coastline."
The update reported that five of the eight surveyed international climate models are showing that an El Niño remains likely to develop by the end of fall, with around half the models expecting the event to become established by September.
The sub-surface temperature map for the 5 days ending July 13 shows waters in the top 75 meters of the eastern equatorial Pacific are more than 3 degrees Celsius warmer than average in some areas. Elsewhere, sub-surface temperatures are generally near average or slightly below average.
From February to June, warm temperature anomalies were detected across the top 100 meters of the equatorial Pacific between the Date Line and the South American coast, but some cooling of the central and eastern equatorial Pacific has taken place over the past month.
NOAA's Climate Prediction Center said July 10 that they expected the El Nino to peak at "weak-to-moderate strength during the late fall and early winter." They estimated the chance of El Niño at about 70 percent during the Northern Hemisphere summer and nearly 80 percent during the fall and early winter.
Closer to home, there is a massive pool of warm water in the Gulf of Alaska, NOAA scientist Nate Mantua said in an email. It is unprecedented in the historical record, he added, and could be sustained if a typical El Niño winter weather pattern occurs in the Northwest.
Such conditions could be hard on next year's juvenile fish migrations and older salmonids already at sea, Mantua said. But so far, West Coast salmon have lucked out, where waters near shore have stayed cool and very productive for fish populations.
Mantua noted that in the past century, warm years in the Gulf of Alaska have favored high juvenile salmon survival and subsequent adult returns (especially for pink, chum, and sockeye) for most of Alaska's rivers (not all, the Yukon being a major outlier in recent years). But the warming over the past year is way out of the historical range -- "so who knows what will happen?" -B. R.
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